Thermostatic regulator



April 16, 1929. E, K, CLARK 1,709,656

THERMOSTATIC REGULATOR Filed April 2; 192'? 2 Sheets-Sheet l lua E, mm nWITNESSES: INVENTOR WQ Eor'l Ki rkwoodClork.

BY y Mge/J April 16, 1929. y E. K. CLARK 1,709,656 n THERMOSTATICREGULATOR Filed April 2, 1927 2 Sheets-Sheet 2 wl N ss s; y INVNTOR WMEarl KirkwoodClQrk,

` ATT'ORNEY Patented pr. 16, 1929.

UNITED STATES Haasse PATET OFFICE.

EARL xIRKWooD CLARK, oF MANSFIELD, OHIO, Assrenon To WESTINGHOUSE Enno-'rn'rc a MANUFACTURING COMPANY,

A CORPORATION F PENNSYLVANIA.

THERMOSTATIC REGULATOR.

Application led April 2,

My invention relates to control devices andv particularly tothermostatic regulators.. An object of my invention is to provide acontrol device that shall be sensitive to changes in conditions ofAtemperature and that shall be of rugged, compact structure.

Another object of my invention is to provide a tempcinture-responsiveelement for a control device .that utilizes the principle ofstraight-bar expansibility, the element being in the form of a spiral.

And a further object of my invention is to provide a thermally actuablecontrol device for controlling electric circuits that shall embody meansfor actuating vcontact members to circuit-making and breaking positionswith a snap motion.

In practicing my invention, means responsive to a condition to becontrolled are provided for selectively actuating a movablecontact-carrying member into, or out of, engagement with a plurality ofindependent contact members.

One embodiment of the means referred to 215V above comp ises athermal-responsive element arranged in the form'of a spiral and spacingvmeans for maintaining the distance between the respective turns of thespiral substantially constant. The inner end of the a0 spiral is fixedand its outer end engages the movable contact-carrying member. A changein temperature ofthe spiral or thermal element is accompanied by achange in length proportional to its original length, its temperatureco-eilicient of expansion, and the change in temperature with respect tothe temperature at which the original length thereof is measured.

By making the thermal-responsive element 40 of spiral form, an elementof great length vis provided; that occupies a relatively small space, ascompared witlrthe same element in the form of a straight bar.

` In the case of a straight metallic element., the greater its length,the greater will be its change in length per degree of change intemperature, whichv change in length may be utilized for actuating acircuit-controlling mechanism. In accordance with my invention, athermal element of relatively great length may be coiled in spiral form,thus reducing the space required by an equivalent 1927. Serial No.180,466.

straight element, whereby the expansion thereof may be utilizedsubstantially in the same manner as when a straight element is employed.

The switch mechanism embodied in the device comprising my invention,consists of two pivoted members, one of which carries a pair of spacedcontact members, and thel other of which carries a contact member thatmoves between the spaced contact members.

The pivoted member to which the spaced contact members are attached, isnormally biased either towards one side or the other of an unstableposition by' means of opposed springs maintained under compression. Ifthe pivoted member is turned on its pivot .towards either the one or theother side of its unstable position, the springs are further compressedand the'pivoted member passes through a state of unstable equilibriumfrom which, on further turning thereof in the same direction, it isactuated abruptly to a position of stable equilibrium by reason of thecompressive forces stored lin the springs.

The pivoted member referred to above is actuated to the one or the otherposition by means of a second pivoted member having a single or commoncontact attached thereto, the second pivoted member being actuated bythe thermal element or spiral member previously mentioned herein. lVhenthe spring-biased pivoted member' passes through its state of unstableequilibrium, the contact carried thereby that engages the common orsingle contact member is actuated out of engagement therewith, thusinterrupting an electric circuit controlled thereby.

In the drawings;

Figure l is a top plan view of the device embodying my invention, aportion being broken away, and a diagrammatic showing of an electriccircuit controlled thereby, l

Fig. 2 is a view, in side elevation, partly in section, of the deviceillustrated in top plan view in Fig. 1,

Fig. 3 is a top plan view of the device, illustrated in Figs. l and 2,showing the deiice in one circuit-controlling position; an

Fig. 4 is like View of the same device in another circuit-controllingposition.

With reference tov Fig. 1 of the drawings,

the energization of a heating unit 11 is controlled by means of anelectro-magnetically operable switch mechanism 12 and atemperature-control device 13. The device 13 eing responsive to athermal condition effected by the heating unit 11, is operable to socontrol the degree of energization ot the heating unit that the thermalcondition is maintained substantially constant.

The heating unit 11 comprises a pair olf resistor elements 14 and 15that are energized from a suitable source ofelectric energy 16. By meansoit the switch mechanism 12, the elements 14 and 15 may be eitherconnected in series or in parallelcircuit relation, depending upon thethermal. condition of the medium surrounding the heating unit 11 towhich the device 13 is responsive.

rlhe switch mechanism 12 is schematically illustrated and comprises, ingeneral, a pivoted bar 17 that carries a pair of contactbridging members18 and 19 at one end thereof. The other end of the bar. 17 is pivotallyconnected to a rod 21, to the ends of which are attached movable coremembers 22 'and 23. The bar 17 is normally biased towards the one or theother side of a vertical position by means of an overcenter spring 24.

The core members 22 and 23 are movable horizontally by means ofsolenoids 25 and 26 that are adapted to be selectively energized from asuitable source of electromotive force 27 by means oi" the controldevice 13. When the magnet coil 26 is energized, the bar 17 is actuatedto the position illustrated in the dra-wings, whereby the resistorelements 14 and 15 are connected in series-eircuit relation to thesource of. supply 16. Thus, an energizing circuit therefor isestablished from conductor 28, conductor 29, Contact bridging member 19,conductor 31, resistor elements 14 and 15, and conductor 32 to conductorof the source of supply 16.

When the coil 25 is energized, the coil 26 being deenergized,contact-bridging mem` bers 18 and 19 are actuated to the left and intoengagement with a plurality of stationary Contact members 34, 35, 36,and 37. It the contact-bridging members 18 and 19 are in this posit-ion,the resistor elements 14 and 15 are connected in parallel-circuitrelation. The energizing circuit of resistor element 14 is therebyestablished comprising conductor 28, conductor 38, contact-bridgingmember 19, conductor 39, resistor element 14, conductor 41,contact-bridging member 18, conductors 42 and 32 toconductors 33, andthat of the resistor element l15 comprising conductor 28, conductor 38,contact-bridging member 19, conductor 39, resistor element 15, andconductor 32 to conductor 33.

The energization of the electromagnet coils 25 and 26 is eected by meansof the 47 coiled in the form of a spiral.

47 is threaded through a spirally coiled temperature-control device 13,as previously stated herein, that comprises, in general, atemperature-responsive element 43, a pivoted member 44 actuated therebyand a contact carrying means 46.

rlhe thermal element 43 consists of a wire The wire tubular member 48that serves to maintain the distance between the adjacent turns of thewire substantially constant. The tubu lar member 48 is positionedbetween a pair of clamping plates 49 that are held in a sub stantiallyiiired position by means of a hollow bushing 51 that is provided with ahead at one end and screw threads at the other Jfor engaging a nut 52.

The inner ends of the wire 47 and the tubular member 48 are squeezedtogether and inserted in a slot 53 (see Fig. 2) and are maintained ixedwith respect to the plates 49. The outer end of the wire' 47 -isadjust-ably attached to the pivoted member 44 by meanstof a screw 54having screwthreaded engagement therewith, the outer end of the tubularmember 48 being free to move along the wire 47. 'lf he member 44 is ofsubstantially L-shape a'nd is provided with a pivot 55 that projectstroni substantially the middle thereof into the hollow bushing 51. rlhemember 44 is biased in one direction by means of a spiral spring 56, theouter end of Which engages al pin 57 carried thereby and the inner endotwhich engages the bushing 51. 58 is carried at the end of the member44 opposite that to which the wire 47 is at taehed.

'llhe contact-carrying means 46 comprises a bar 59 that is pivotallysecured to one of the plates 49 by means of a. bolt 61 that eX- tendsthrough the plate 49 and the bar. rl`he ends of the bar may be in'ovidedwith notches of substantially il-shape, for a purpose to be hereinafterset i'orlh. A pair of contact-supporting brackets 62 and 63 otsubstantially L-shape, extend laterally from the bar 59 and are suitablysecured thereto by such means as screws or rivets, and insulatedtherefrom by suitable insulation 64. A short strip of insulatingmaterial 65 is secured to the brackets 62 and 63, near their outer ends,to maintain these ends fixed relatively to each other. Switch contacts66 and 67 are carried at the respective outer ends of the members 62 and63 and are adapted to be engaged by the contact member 58.

The position occupied by the bar 59, as illustrated in Fig. 1 of thedrawings, is unstable, the bar being biased towards a stable positionlocated at either the one side or the other thereof, by means of a pairof springs 68 oit substantially sinuous shape. The inner ends of thesprings en- A contact member lll) igroaete gage the notched ends of thebar 59, and the outer ends thereof abut against a pair of lugs 71 thatare secured to the top clamping plate 49. The springs 68 are of suchlength that they are normally maintained in compression, but tend toelongate when the bar 59 has been actuated to a stable position.

lil the member 44 is turned in a counter clock-Wise direction, thecontact. members 58 and`67 `will .be maintained in engagement, and thebar 59 will be turned, onV its pivot 6l, to a position slight-ly beyondthat illustrated in llig. l and in a counter clockwise direction. Whenthe latter position is reached, the springs 68 are so dellected thatbothof them tend to elongate, thereby .causing the bar 59 to move abruptlytrom this position to a stable position whereby the contact member 67becomes disengaged from contact 58 with a snap motion. However, Whenthis stable position is reached, the contact 66 immediately engagesthecontact58 (see Fig. 3). i

'lll the bar 44 is turned in a cloclewise direbtion, the bar 59 iscaused to be turned on its pivot in a clock-wise direction also to aposition slightly beyond that of unstable equilibrium (see Fig. l) tromwhich position it is caused to be moved with a snap motion because otthe elongation ot the springs 68 to the stable position illustrated inFig. 4., Thus, the contact member 66 is positively disengaged fromcontact member 58 with a sudden, snap motion. But, innnediately upon thedisengagement of the contacts 58 and 66, the contact 58 makes engagement`With the contact/6lv (see F ig. 4.)

ln order to limit the degree of movement of the bar 59, a pair of lugsare attached to the plate 49 in the path ot movement of the brackets 62and 63.

llt it is desired that the contacts 66 and 67 shall not immediately makeengagement with the contact 58, upon the-actuation. of the bar 59 to theone or the other of its stable positions (see Figs. 3 and 4), thebrackets 62 and 63 may be spaced farther apart than is indicated in thedrawings. ln this event, a certain interval oit time will elapse betweenthe disengagement of contacts 58 and 66 and the re-engagement ofcontacts 58 and 67 or vice versa. Since the contacts 66, 67 and 58 moveingthe same, general direction, and engagement and disengagement thereofis etlected by the bar 59 andthe ,springs 68, the contact 58 may beconsidered to be stationaryrelatively to the contacts 66 and 67.

The energizin circuit or the solenoid 26, being establishe by theengagement of contacts 58 and 67, comprises one terminal of the sourceof electric energy '27, contacts 58 and 67, conductor l72coil 26,conductor 73 and the other terminal of the source 27; The energizingcircuitl of the coil 25, being established by the engagement ol contacts58 and 66, comprises one terminal, the source of yelectric energy 27,contacts 58 and 66, conwi 1 ecreases in enc an causes re 47 d l l5th dthe bars 44 and 59 to turn on their pivots in a counter-clockwisedirection, the cont-acts 58 and 67 being in engagement. lf thetemperature continues to decrease, the movement oiu thek bars in acounter-clockwise direction Will continue until the bar 59-movesabruptly to the position illustrated in Fig. 3 to eect engagement of thecontacts 58 and 66, and energization ot the solenoid 25. Upon theenergization ot the solenoid 25, the bar 17 is so actuated that thebridging members i8 and 19 engage the stationary contacts 34 to l37inclusive, whereby the resistor elements i4 and l5 are connected inparallel, thereby increasing the heat-generating capacity of the heatingunit ll.

`When the temperature of the Wire 4'? has increased to a predeterminedvalue in response to the increased energization ot the heating unit il,its length increases also until.

the bar 44 has actuated the bar 59 in a clockvvise direction through itsunstable position (see Fig. l) to the stable posit-ion illustrated inFig. 4. Thus, disengagement ot the contacts 58 and 66, deenergization ofthe solenoid 25, and re-engagement o the contacts 58 and 67 andconsequent reenergization ot the solenoid 26 are e'ected. llVhen thesolenoid 26 is energized, the bar 17 is actuated to the positionillustrated in F ig. l, whereby fthe resistor elements are againconnected in series-circuit relation to the -supply con- 'fductors 28and 33.

rlhe initial position of the movable member 4&4 may be adgusted by meansof the screw 54.

Since the Wire 47 slides along the tubular member 46, a slight amount offriction is encountered which may be compensated for by means ot thecoil spring 56.

By providing a thermal element ol the type illustrated in Figs. l and 2of the draw- `ings, a thermal-responsive element, which consists ot asingle metallic Wire or bar, may be utilized for actuating acircuitcontrolling mechanism. The thermal element comprises the Wire 47Wound in the form ot a spiral that is threaded Within 4the spiraltubular member 48 so that any'increase or decrease in length .ot thewire 47 results in its sliding Wit the tube 48.. The eect ot-a Wire 47,

boring tlie :form ot o spiral, when subjected to tem o ure, issubstantially tbe seme es if were disposed in n strati lit line,-

A Wire extending in e linear direction would occupy o much greater spocethen tliet occupied when coiled in the term illus-y trnted in Figs. land 2 of the drawings. Flirt-lier, e, 'Wire of the size illustrated inthe dren/ings would be impreeticable when used es linear expansionmember since tbe rigir ity tbereol2 would be insuicient to render tbedevice practicable.

l/Vbile tbe clamping plates 49 are illustrated as being,r of e solidnature, it is to be understood that they nifty be so slotted that e.lorgge iportion ofthe metal is removed there- `from, thus reducing thethermal capacity thereof. Likewise, the tubular member 48 moy be proviced with e plurality ol opertures in order tlisttlie temperature, toWbicli the WireJ-' is to be responsive, muy affect it directly, 'therebyreducing its thermal leg; re-

lotiifely to that 'which would be present in the absence oit suoliapertures.

Voriousl modifications may be mede in the device embodying my inventionVWithout departing trom tbe spirit end scope thereof. li desire,therefore, that only such limitations elio-ll be placed thereon as areimposed by the prior ort end tbe appended claims,

claim es invention:

l. A temperaturecontrol device comprise pii/otelly mounted member, eContact irclienism sctuetecl thereby, end tbermci rcsoonsife meen :toreotueting seid pivotally mounted member, seid ineens' comprising ebellow spiral tube, e metallic member bev,- e relotii/ely hightemperature co-ctiicent ot expansion disposed Within seid spiral tube,inetrl ic member bemg lined et end ond oper isely connected to seid ntelmember tbe other ltcb cor '.fs-.ingn pivotolly y oi contects csrorings`tor boldy moon ed member one relity of stoble oositions,

effective to ec'tnete member from msteble position to one or enotlierot' seid stable positions With s snep motion, a common contact normallyengag ing one oit seid plurality ci contacts, and means responsive to e,conditionto be controlled for actuating ssicl ,member pest its unstableposition whereby disengagement ot one of said plurality oi contacts fromsold common contact iseliected.

3. The combination with e. pivoted mene ber, spring meenstor holdingseid pivotcd member in either one or enotlier of s plural-- ity etstable positions, seid spring ineens loe-- ing effective to octiieteseid pivoted member from en unstable lposition located between seidstable positions to one of seid stable positions with o snno motion, andspaced eport contacts carrier by seid pivoted meniber, of s secondpivoted member normally engaging one off seid Contact members, andineens tor actuating; the second pii/otefl meniber whereby seid firstnamed pivoted meniber is ectnnted its unstable position to efiectdisengagement of one ot said contacts from seid second pivoted member;

' il. A control devi-ce comprising e pi'votelly mounted member,resilient ineens Afor bolding seid member in eitber one or enotber of eplurality oi stnble positions, seid springs coscting to cause saidmember to be in an unstable position when seid member is in e positionintermediete seid stable positions, n plurality of movoble contactscontrolled by seid member, e common Contact Vtor engaging one oronotlier of seid movable contncts, seid common Contact being stationaryrele.n tively to und normally one of seid movable contacts, ond. meansresponsive to o condition to be controlled for actuating said membertlirougli its nnste. le position Where by disengagement of one oit seidmovable contacts from seid common contact and cngegemcnt of enotlier ofseid movable con.- tircts 'therewith is iteCted,

lin testimony wberr T subscribed my i927,

bis

